赖氨大黄酸对KK/HlJ糖尿病小鼠胰岛素抵抗的改善作用及其机制

目的：探讨赖氨大黄酸（RHL）对链脲佐菌素（STZ）诱导的KK/HlJ糖尿病（DM）小鼠胰岛素抵抗的改善作用，并阐明其作用机制。方法：腹腔注射STZ （50 mg·kg^-1）并给予DM专属饲料制备KK/HlJ小鼠DM模型。将48只小鼠分为正常对照组、模型组、低剂量RHL治疗组（25 mg·kg^-1）和高剂量RHL治疗组（50 mg·kg^-1），每组12只，共治疗16周。采用葡萄糖氧化酶法检测各组小鼠空腹血糖（FBG）、总胆固醇（TC）和甘油三酯（TG）水平，HE染色观察小鼠胰腺组织形态表现，免疫组织化学法检测小鼠胰岛组织中胰岛素水平，酶联免疫吸附法（ELISA）检测小鼠血清胰岛素、C反应蛋白（CRP）和肝脏组织中肿瘤坏死因子α（TNF-α）及白细胞介素6（IL-6）水平，Western blotting法检测小鼠肝脏组织中糖原合成相关基因（PI3K、AKT和GSK-3β）的磷酸化表达水平。结果：与模型组比较，低和高剂量RHL治疗组小鼠FBG、TG和TC水平降低（P<0.05），胰岛素水平无明显变化（P>0.05）。与模型组比较，低和高剂量RHL治疗组小鼠血清CRP水平和肝脏组织中TNF-α和IL-6水平降低（P<0.01）。HE染色，与模型组比较，低和高剂量RHL治疗组小鼠胰岛形态有一定恢复，偶见炎症浸润；免疫组织化学染色，与模型组比较，低剂量RHL治疗组小鼠棕色颗粒状物质明显减少，而高剂量RHL治疗组小鼠胰岛中未见棕色颗粒状物质。与模型组比较，低和高剂量RHL治疗组小鼠糖原合成相关基因PI3K、AKT和GST-3β磷酸化表达水平升高（P<0.01）。结论：RHL对STZ所致KK/HlJ DM小鼠胰岛素抵抗有改善作用，其机制可能与RHL促进糖原合成有关。

Improvement effect of rhein lysinate on insulin resistance of KK/HlJ diabetic mice and its mechanism

Objective:To explore the improvement effect of rhein lysinate (RHL)on the insulin resistance in the KK/HlJ diabetes mellitus (DM ) mice induced by streptozotocin (STZ ), and to elucidate its mechanism. Methods:The KK/HlJ diabetic mouse models were made by intraperitoneal injection of STZ (50 mg· kg-1 )and fed with DM diet.A total of 48 mice were divided into normal control group,model group,low dose of RHL group (25 mg·kg-1 )and high dose of RHL group (50 mg·kg-1 ) (n= 12).All the mice were treated for 16 weeks. The levels of fasting glucose (FBG),total cholesterol (TC)and triglyceride (TG)of the mice were measured by glucose oxidase method.HE staining was used to observe the morphology of pancreas tissue of the mice.The insulin level in pancreas islet tissue was detected by immunohistochemistry method.The levels of insulin and of C reactive protein (CRP)in serum and tumor necrosis factorα(TNF-α)and interleukin 6 (IL-6)in liver tissue of the mice were detected by enzyme linked immunosorbent assay (ELISA)method.The expression levels of glycogen synthesis related genes (PI3K,AKT and GSK-3β)phosphorylation were detected by Western blotting method. Results:Compared with model group,the levels of FBG,TG and TC of the mice in low and high doses of RHL groups were significantly decreased (P < 0.05),but there was no significant difference in the insulin level (P >0.05).Compared with model group,the levels of CRP in serum and the levels of TNF-αand IL-6 in liver tissue of the mice in low and high doses of RHL groups were significantly decreased (P <0.01).The HE staining results showed that compared with model group,the islet morphology of the mice in low and high doses of RHL groups was partially restored,and the occasional inflammatory infiltration was observed.The immunohistochemical staining results showed that compared with model group,the brown granular substance in the islets of the mice in low dose of RHL group was significantly reduced,which was disappeared in high dose of RHL group.Compared with model group,the expression levels of glycogen synthesis related genes (PI3K,AKT and GST-3β)phosphorylation of the mice in low and high doses of RHL groups were increased (P <0.01).Conclusion:RHL has improvement effect on the insulin resistance in the KK/HlJ DM mice induced by STZ,and the mechanism may be related to promoting the glycogen synthesis.